1. Field of the Invention
This invention relates to the field of electret transducers, and particularly to a transducer in which the electret material is an inorganic insulator, preferably with more than one layer, and to a method of forming an electret structure suitable for use in a transducer.
2. The Prior Art
Heretofore electret materials have usually been high polymers or other organic materials. In the formation of a complete electret structure, it has been necessary to attach a thin metal layer by means of adhesive to one surface of the insulating material. It is difficult and time consuming to perform this step, particularly in mass production. Furthermore, such organic materials must not be subjected to very high temperatures.
It is one of the objects of the present invention to provide an improved electret structure and a method of making the same.
Another object of this invention is to provide an electret structure comprising inorganic electret material.
A further object of this invention is to provide an electret structure capable of accepting a substantially higher charge per square centimeter than the high polymer electrets in use heretofore.
A still further object of this invention is to provide an electret structure that is resistant to heat.
Further objects will become apparent from the following specification together with the drawing.